This project will investigate the association between neurodevelopmental impairment and single suture craniosynostosis (SSC), defined as the premature fusion of a single cranial suture. This cohort of participants with SSC (n=240) and controls (n=240) were recruited in infancy (R01 DE 013813) and assessed at three time points: (1) prior to cranioplasty (age 6 months on average);(2) age 18 months;and (3) age 3 years. The long term objective of this project is to better understand how the developing cranium affects human growth and function. Existing studies of school-age children with SSC (primarily case record reviews or evaluations of small clinical samples) suggest a substantially elevated risk of learning, attention and behavior problems. Clarification of the impact of SSC is an important public health objective because families currently receive conflicting information regarding the rationale for cranioplasty. Some health providers believe that this procedure is only necessary to reduce craniofacial disfigurement, while others believe that the procedure prevents or minimizes neurodevelopmental disorder and brain deformation. Specific aims are to: 1) Compare the neurodevelopment of school-age children with and without SSC across seven domains of neuropsychological functioning (intelligence, language abilities, attention and executive function, learning and memory, visual-motor skills, processing speed, and academic achievement);2) Develop predictive models of functional outcomes for children with SSC at age 7 using data obtained during infancy/toddler assessments;3) Examine neurobehavioral development as a function of pre- to post-surgery change in severity of synostosis, as determined by quantification of CT scans;4) Test the hypothesis that children with SSC will show greater degree of structural abnormality and decreased brain volumes on MRI when compared to age-matched controls.